The present invention relates generally to a switch, and in particular to a switch having an overload protection mechanism for operation safety.
A switch is operable between an ON (connected) state and an OFF (disconnected) state for control of power supply or electrical signal transmission. For a power switch, overheating and burning caused by overload resulting from undesired shorting is one of the major concerns of operation safety. Some switches available in the market are provided with safety mechanism that automatically cuts off power supplied therethrough in order to eliminate the potential risk of overheating and burning. Such switches, however, have complicated structures, making costs high and manufacture difficult.
It is thus desirable to have a switch structure that is simple in structure but possesses operation safety feature.
An object of the present invention is to provide a switch having a simple structure while capable of operation safety.
Another object of the present invention is to provide a switch of low costs while having overload protection.
A further object of the present invention is to provide a switch which is easy to manufacture.
To achieve the above objects, in accordance with the present invention, there is provided a switch comprising a casing having a bottom to which first and second conductive blades are mounted. The second blade has a top edge forming a notch for receiving a seesaw plate and allowing seesawing of the seesaw plate. A conductive strip made of a material that bends when subject to a temperature rise has an end fixed to the first blade and an opposite, free end forming a cantilever. The seesaw plate is movable between an engaged position where a first end of the seesaw plate engages the free end of the conductive strip thereby forming an electrical connection between the first and second blades and a disengaged position where the seesaw plate disengages from the conductive strip thereby electrically disconnecting the second blade from the first blade. A control button is movably received in a top opening of the casing and has a driver assembly mounted thereto. The control button is movable between a first position wherein the driver assembly drives the seesaw plate toward the engaged position and a second position where the driver assembly drives the seesaw plate toward the disengaged position. When an excessive current flows through the conductive strip, causing a temperature rise in the conductive strip, the conductive strip bends and separates the free end thereof from the seesaw plate thereby breaking the electrical connection between the first and second blades.